1. Field of the Invention
This invention relates to architecture of integrated circuits. More particularly, it relates to methods for providing uniform power distributions internally to large integrated circuit (IC) designs.
2. Background of Related Art
Integrated circuits (ICs) are a fact of life that has transformed society over decades of continued development and miniaturization.
While initially many ICs operated with an input 5 volt power source, more recent technology advances have developed low voltage technologies that utilize lower voltage power supply input, e.g., 3.3 volt, 2.5 volt, 1.5 volt, etc.
For instance, FIG. 4 shows a conventional architecture for powering various elements of an IC 450 from power rails 400 & 401. Powered sub-circuit elements 402-404 of a typical integrated circuit may contain digital components (e.g., custom cell/logic gates, memory, etc.), analog sub-circuits (e.g., NTSC video decoder logic, analog audio logic, etc.), and/or circuits with a mix of analog and digital (e.g., audio CODECs).
Until very recently, voltage regulation was most often performed external to a given IC. Voltage regulation ‘regulates’ or controls a general power supply input to a lower, more stable voltage level.
Due largely to trends to increase the number of functions in a given IC, more and more devices which were otherwise connected in an electrical circuit board including the IC have been integrated into the given IC. This is done for miniaturization (space/form factor) as well as cost sensitivity considerations. In some instances, an IC has been developed that implemented a voltage regulator within an IC.
The internally implemented voltage regulation element in the conventional IC takes in an external voltage, regulates this external voltage by setting an output threshold/voltage, and distributes this throughout a power rail that is routed as necessary around the entire IC.
For instance, FIG. 5 shows another conventional architecture for power various sections or elements of an integrated circuit 550. As shown in FIG. 5, various elements 402-404 of a given IC 550 are powered between a power rail 400 that extends as necessary about the IC 550, and a ground rail 401 which similarly is routed as necessary about the IC 550, with the added integration of a voltage regulator 500 appropriate for the particular application.
ICs are increasingly getting bigger-not necessarily in physical package size but in the sense that they are including greater numbers of functions, features, etc. Thus, while miniaturization continues to progress over time, ICs are similarly progressing and are including greater numbers of functional circuit elements.
Given the conventional power rail approach, it is recognized by the inventor of the present application that internal power distribution may not be uniform. This is depending in large part both on the ever-increasing component density of the IC device 550, as well as on where in particular the voltage regulating element is physically located within the IC structure 550. Thus, if power is introduced by the voltage regulator 500 as shown in FIG. 5, the present inventor appreciates that the regulated voltage will be somewhat higher for the first element 402 powered by the power rail 400 of the IC than for the last element 404 powered by the power rail 400. While the voltage drop along a power rail within an IC may not pose a problem to designers for analog circuits or in “small” digital chip developments, it will become increasingly problematic as ICs become denser, larger in physical structure, and/or when additional functionality with un-bounded duty cycles become prevalent. Moreover, as the voltage level of power supplies lowers (e.g., to 3.3 v, 2.5 v, 1.5v, etc.), non-uniformity in voltage along the power supply rail will become more significant.
Thus, the present inventor appreciates that there is a need for improved voltage distribution and/or power management architecture and techniques.